Axial-flow PAT Efficiency Estimation via 1D Flow Model
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Solution Overview
Problem
Current methods for estimating the optimal efficiency point parameters and performance curve of axial-flow Pump as Turbine (PAT) power generation mode are complex, resource-intensive, and difficult to apply in engineering practice, lacking a simple and convenient solution.
Innovation Solution
A method involving calculations for axial velocity, flow rate, hydraulic head, and efficiency parameters using specific formulas and segmenting the flow channel to estimate optimal efficiency point parameters, followed by performance curve estimation based on similarity hypotheses and hydraulic head-output power relationships.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If model test or three-dimensional CFD numerical simulation is used to predict hydropower characteristic, then prediction reliability and accuracy are improved, but device complexity and loss of time increase
Solution Approach 1:
The patent uses a simplified one-dimensional flow model that copies the essential physics of the three-dimensional flow without requiring complex CFD simulations. This allows prediction of hydropower characteristics with acceptable accuracy while avoiding the high computational costs and complexity of full 3D numerical simulations
Solution Approach 2:
The patent extracts only the most critical flow characteristics and energy conversion relationships from the complex three-dimensional flow field, formulating a simplified one-dimensional model that captures the dominant physics while eliminating unnecessary complexity
2Reliability
If model test is used to predict hydropower characteristic, then prediction reliability is improved, but loss of time and loss of substance increase
Solution Approach 1:
The patent replaces physical model testing with a theoretical calculation model based on one-dimensional flow equations. This substitution eliminates the need for building physical test rigs, installing instrumentation, and conducting time-consuming experimental campaigns while providing reliable predictions through validated theoretical relationships
3Measurement precision
If numerical simulation is used to predict hydropower characteristic, then prediction accuracy is improved, but loss of time and device complexity increase
Solution Approach 1:
The patent extracts only the essential energy conversion relationships and flow characteristics needed for hydropower prediction, formulating a simplified one-dimensional model that provides accurate results with minimal computational effort compared to full three-dimensional CFD simulations
4Ease of manufacture
If manufacturers do not test performance of the PAT in power generation mode, then cost is reduced, but loss of information increases
Solution Approach 1:
The patent uses a theoretical model that copies the performance characteristics expected in power generation mode based on design parameters and pumping mode data. This provides the necessary performance information without requiring actual physical testing, thereby reducing costs while maintaining information availability
Solution Approach 2:
The patent enables performance prediction to be performed during the design phase using theoretical calculations, providing performance information before manufacturing and testing. This preliminary estimation allows for informed decision-making without incurring the costs of actual performance testing
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This method provides accurate and efficient prediction of energy parameters, facilitating unit selection and design, with high adaptability and reliability within the allowed operating range of axial-flow PATs, reducing calculation time and improving accessibility.
Implementation Method 1
calculating an axial velocity νml,t of an optimal efficiency point in a power generation mode by utilizing the following formula: where νml,t is an axial component of an absolute velocity (m/s), Qpb is an flow rate of an optimal efficiency point in a pumping mode (m3/s), R is a radius of an airfoil position (m), n is a rotational velocity of an impeller (r/min), D is impeller diameter (m), dh is a diameter of a hub (m), βe is an impeller airfoil setting angle)(°, and βe,g is a guide blade setting angle (°)
Data Source
AI summary
Provided is a method for estimating optimal efficiency point parameters in an axial-flow PAT power generation mode, including: I1, calculating an axial velocity of an optimal efficiency point; I2, calculating a flow rate of the optimal efficiency point; I3, calculating a theoretical hydraulic head; I4, calculating a frictional hydraulic head loss and a local hydraulic head loss of each segment; I5, calculating an output power of the optimal efficiency point; I6, calculating a hydraulic head of the optimal efficiency point in a power generation mode; and I7, calculating an optimal efficiency. Further provided is a method for estimating a performance curve in an axial-flow PAT power generation mode based on the above method for estimating an optimal efficiency point parameter, including: II1, calculating a normalized flow-hydraulic head curve; II2, calculating a normalized hydraulic head-output power curve; and II3, calculating a hydraulic head-efficiency curve.